Polymercaptans and their preparation from epithio compounds



United States Patent 0 3,369,040 POLYMERCAPTANS AND THEIR PREPARATIONFROM EPITHIO COMPOUNDS William De Acetis, Berkeley, Calif., assignor toShell Oil Company, New York, N.Y., a corporation of Delaware N 0Drawing. Continuation-impart of application Ser. No. 63,961, Oct. 21,1960. This application Oct. 19, 1962, Ser. No. 231,852

11 Claims. (Cl. 260-468) This application is a continuation-in-part ofmy application Ser. No. 63,961, now abandoned filed Oct. 21, 1960.

This invention relates to new sulfur-containing compounds and to theirpreparation. More particularly, the invention relates to newpolymercaptans containing at least four -SH groups which areparticularly valuable as curing agents for polyepoxides, and to a methodfor preparing the new polymercaptans.

Specifically, the invention provides new and particularly usefulpolymercaptans which possess at least two SH sH groups, and preferably 2to 6 such groups, and in addition preferably an activating group in thevicinity of the SH SH groups, such as, for example, an ester, ether,amide, imide or urethane group, or a cyclic group.

As a special embodiment, the invention further provides a process forpreparing the new polymercaptans as by reacting polythiiranes withhydrogensulfide, or more preferably by reacting materials, such aspolyepoxides, polyhalides, polythirranes and polythiocyanates, withxanthates to form cyclic trithiocarbonates, and then reducing thetrithiocarbonates to form the polymercaptans.

The invention also provides a method for using the above-described newpolymercaptans for curing polyepoxides which comprise mixing andreacting the polyepoxide which contains more than one vic-epoxy groupwith one or more of the above-described polymercaptans, preferably inthe presence of an activator, such as a tertiary amine.

Polyepoxides, such as glycidyl polyethers of polyhydric phenols, can becured by reaction with various types of amines, acids and anhydrides.These materials, however, are not particularly effective when used atlower temperatures such as the order of 0 to C., as a cure at thistemperature takes considerable time. This defect places considerablelimitations on the use of epoxy resins for applications such astreatment of roads, runways, and the like which must be accomplishedover a wide range of temperatures.

It is an object of the invention, therefore, to provide a new class ofpolymercaptans which are particularly useful as low temperature curingagents for epoxy resins. It is a further object to provide newpolymercaptans and method for their preparation. It is a further objectto provide a method for preparing new polymercaptans from polythiiranecompounds. It is a further object to provide a method for preparing newpolymercaptans from polyepoxides, polyhalides, polyepisulfide,polythiocyanates and the like. It is a further object to provide newpolymercaptans which can be used to cure epoxy resins to hard insolubleinfusible products at low temperatures. It is a further object toprovide new polymercaptans which can be used to cure epoxy resins toform products having excellent hot hardness and good solvent resistance.It is a further object to provide new cyclic trithiocar- 3,369,040Patented Feb. 13, 1968 bonates which are particularly useful andvaluable in industry. These and other objects will be apparent from thefollowing detailed description thereof.

It has now been discovered that these and other objects may beaccomplished by the new polymercaptans of the present invention whichcomprise products possessing at least two SH SH t t groups, andpreferably 2 to 6 such groups and in addition preferably an activatinggroup, such as, for example, an ester, ether, amide, imide or urethanegroup or a cyclic group. It has been surprisingly found that theseparticular compounds are particularly effective for the cure ofpolyepoxides when used at the lower reaction temperatures such as, forexample, from 0 C. to 15 (1.; although the reaction takes place at thelower temperatures and resulting products still possess excellenthardness, good heat resistance and good solvent resistance.

The new polymercaptans of the present invention are those compoundspossessing at least two sH SH groups, and preferably 2 to 6 such groups,and in addition preferably an activating group in the vicinity of the SHsH groups, such as, for example, an ester, ether, amide, imide orurethane group or cyclic group. In addition, the compounds may bealiphatic, cycloaliphatic, aromatic or heterocyclic and may be saturatedor unsaturated. The compounds may also be monomeric or polymeric.

Examples of the new compounds include, among others,polymercapto-substituted etherssuch as tri(2,3-dimercaptopropyl) etherof glycerol, di(3,4-dimercaptobutyl) ether of diethylene glycol,di(2,3-dimercaptohexyl) ether of 1,4-butanediol,di(2,3-dimercaptocyclohexyl) ether of l, 5-pentanediol,tri(2,3-dimercaptopropyl) 1,2,6-hexanetriol, di(2,3-dimercaptopropyl)ether of sulfonyldipropanol, di(2,3-dimercaptopropyl) ether of1,4-dimethylolbenzene, tri(2,3-dimercaptobutyl) ether oftrimethylpropane, poly(2,3-dimercaptopropyl) ether of polyallyl alcohol,di(3,4-dimercaptobutyl) ether, di(2,3-dimercaptopropyl) ether,di(2,3-dimercaptopropyl) ether of resorcinol, di(3,4-dimercaptohexyl)ether of resorcinol, tri- (3,4-dimercaptooctyl) ether of1,3,5-trihydroxybenzene, di(2,3-dimercaptopropyl) ether of2,2-bis(4-hydroxyphenyl) propane, di(3,4-dirnercaptobuty1) ether of2,2-bis- (4 hydroxyphenyl)butane, tetrakis(2,3 dimercaptopropyl) etherof 1,1,2,2-tetra(4-hydroxyphenyl)ethane, tetrakis(3,4-dimercaptobutyl)ether of 1,1,5,5-tetra(4-hydroxyphenyDpentane, di(3,4-dimercaptohexyl)ether of 2,2 'bis(4 hydroxyphenyDsulfone, di(3,4-dimercaptobutyl) etherof 2,2- bis(4-hydroxy-5-methoxyphenyl) 1,1-dichloropane, and the like.

Other examples include the polymercapto-substituted esters, such as,di(2,3-dimercaptopropyl) phthalate, di- (3,4-dimercaptobutyl)tetrachlorophthalate, di(2,3-dimercaptopropyl) terephthalate,di(3,4-dimercaptohexyl) adi pate, di(2,3-dimercaptobutyl) maleate,di(2,3-dimercaptopropyl) sulfonyldibutyrate, di(3,4-dimercaptooctyl)thiodipropionate, di(2,3-dimercaptohexyl) citrate,di(3,4-dimercaptoheptyl); cyclohexanedicarboxylate,poly(2,3-dimercaptopropyl) ester of polyacrylic acid, poly(2,3-dimercaptohexyl) ester of polymethacrylic acid, and the like, and esterswherein the mercapto group is or are in the acid portion of themolecule, such as 2,3-mercaptopropyl 2,3-dimercaptopropionate,3,4-dimercaptohexyl 3,4 dirnercaptohexanoate, 2,3-dimercaptopropyl2,3-dimerca-pto 4-methylbutyrate, diethyl-8,9,12,l3-tetramercaptoeicosanedioate, diethyl7,8,11,12-tetramercaptooctadecanedioate, dibutyl6,7,10,11-tetramercaptohexadecanedioate, dibenzyl 8,9,12,13tetramercaptoeicosanedioate and the like.

Still other examples include the polyesters such as theoreticallyobtained by reacting a polycarboxylic acid or anhydride with apolyhydric alcohol, such as, for example, polyesters of8,9,12,13-tetramercaptoeicosanedioic acid and glycerol, hexanetriol,polyethylene glycol and the like, polyesters of6,7,10,1l-tetramercaptohexadecanedioic acid and ethylene glycol,glycerol, 1,2,6-hexanetriol, polypropylene glycol and the like.

Still other examples include the polymercapto-substituted hydrocarbons,such as, for example, 2,2-bis(2,3-dimercaptocyclohexyl) propane,1-(2,3-dimercapt0propyl) 2,3-dimercaptocyclohexane, 1,4 bis(2,3dirnercaptopropyl) benzene, 2,4,6-tri(2,3-dimercaptopropyl) phenol, 1,2,4,5 tetrarnercaptocyclohexane, and 2,4,6 tri(3,4 dimercaptobutyl)benzoic acid and the like.

Still other examples include the polymercapto-substituted polyamines,such as, for example, N,N-bis(2,3-dimercaptopropyl) phthalamide,N,N-bis(2,3-dimercaptopropyl) adipamide, N,N-bis(2,3-dimercaptopropyl)maleic acid amide and the like. Also included are examples ofpolymercapto-substituted polyarnines themselves, such asN,N-bis(2,3-dimercaptopropyl) aniline, N,N-bis(2 ,3-dimercaptopropyl)phthalamide, N,N-bis(2,3-dimercaptoproply) adipamide,N,N-bis(2,3-dimercaptopropyl) maleic Still other examples include thepolymeric polymercaptans, such as may be obtained by polymerizing orcopolymerizing dimercapto-substituted unsaturated compounds as1,2-dimercapto-3,4-butene and the like, or by homopolymerization orcopolymerization of polyunsaturated compounds, such as butadiene orisoprene, and converting the unsaturated groups remaining in the polymerto dimercapto groups by the hereinafter described technique ofepoxidation, conversion of the epoxide to the epithio group and reactingthat with hydrogen sulfide. Examples of monomers that may becopolymerized with the abovenoted polyunsaturated compounds include,among others, acrylonitrile,styrene, alphamethylstyrene, methylmethacrylate, methyl acrylate, ethyl acrylate, maleic acid, diethylmaleate, allyl acetate, vinyl acetate, vinyl benzoate, chloroallylh'enzoate, divinyl ether of ethylene glycol, dimethacrylate ester ofethylene glycol and the like, and mixtures thereof.

Particularly preferred polymercaptans include the polymercaptosubstituted ethers containing from 2 to 6 SH SH- groups and not morethan 24 carbon atoms, and particularly those of the formula wherein n is2 to 6 and R is a radical derived from a polyhydric alcohol or phenol byremoving n OH groups.

Also particularly preferred polymercaptans include thepolymercapto-substituted esters containing from 2 to 6 s11 an .C G

groups and not more than 24 carbon atoms, and especially those of theformula wherein n is an integer of 2 to 6 and R is a residue of apolycarboxylic acid obtained by removing n carboxyl groups.

4'. Also especially preferred are the polymercapto-substitutedhydrocarbons containing from 2 to 6 ?H ?E Q groups and not more than 24carbon atoms, and particularly those of the formula as part of a cyclicstructure as SH HS:I [SH HS SH HS SH Hs SH HS SH HS I 1-811 -SH or thosewherein the HS SH S H $11 R C is attached to the ring, such as sH SH Lonn1 OHrCH CH-CH:

1 I GHz-GH2 SH SH SH SH 1 1 SH SH CH-OH: SH sH I l t l sH SH ore-0HComing under special consideration are those of the wherein each X isthe same or difierent organic or inorganic bivalent radical, n is 0 to20, R is a bivalent hydrocarbon radical and R is hydrogen or ahydrocarbon radical.

The new polymercaptans of the present invention can be prepared by avariety of methods. They may be prepared, for example, by reactingpolythiirane compounds with hydrogen sulfide. The polythiirane compoundsthemselves may be prepared by reacting polyepoxides with a thiocyanatesuch as ammonium thiocyanate or a metal thiocyanate as potassiumthiocyanate. Detailed description of this method of preparation as wellas resulting polythiiranes may be found in my copending application Ser.No. 63,961, now abandoned, filed Oct. 21, 1960, and so much of thedisclosure of that application pertinent to these compounds and theirpreparation is incorporated herewith.

The reaction of the above-described polythiirane compounds and thehydrogen sulfide may be accomplished by merely combining the componentstogether, preferably in the presence of a catalyst. The proportions inwhich the polythiirane compound and the hydrogen sulfide are combinedmay vary over a wide range depending on the properties desired and thefinished product, i.e. whether one desires a monomeric product orpolymeric. If one desires a monomeric product, it is preferred to employthe hydrogen sulfide in excess. Preferably one employs at least 5 molesof H 8 per thiir-an group to be converted. Particularly preferredequivalent ratios of H 5 to epoxide vary from 5:1 to 50:1. Polymericproducts are obtained in larger amounts when one employs the hydrogensulfide in lesser amounts. Polymeric polymercaptans are obtained, forexample, when the components are added in approximately chemicalequivalent amounts.

In preparing the new products, it is generally preferred to saturate asuitable solvent or diluent with the hydrogen sulfide and then add thepolythiirane compound to solvent or diluent so as to keep the hydrogensulfide in excess and prevent possible gelation. This order of additionsalso preferred in the case of the formation of the polymeric products.

The solvent or diluent employed in the process may be any suitable inertmaterial which will give the necessary fluidity but will not react withthe reactants or products. Suitable solvents include toluene, benzene,dioxane, tetrahydrofuran, dibutyl ether, alcohols and the like.

The reaction may be accomplished without the use of catalysts but it issometimes desirable to employ catalytic quantities of materials, such asalkaline catalysts as so dium hydrosulfide, sodium ethoxide, sodiumphenoxide, sodium hydroxide, and the like, and tertiary amines, such astriethylamine, pyridine, benzyldimethylamine, and the like. The amountof'these catalysts will generally vary from about 0.01% to 5% by weight.

The temperature employed in the reaction may vary over a considerablerange. In general, the reaction between the polythiirane and hydrogensulfide in the presence of the aforementioned catalysts will proceed ata satisfactory rate at temperatures as low as 15 C. to room temperature.Preferred temperatures range from about 0 C. to, room temperature orabout 20 C. Increased reaction rates may be obtained by application ofheat and temperatures up to say 50 C. may be successfully employed. Insome instances, such as where an excess of hydrogen sulfide is to beemployed, it may be desirable to conduct the reaction at the lowertemperatures so as to increase solubility of hydrogen sulfide in thereaction mixture.

The reaction is conducted in the substantial absence of molecularoxygen. This is preferably accomplished by employing an inert atmospheresuch as in the presence of hydrogen sulfide vapor or by the addition ofnitrogen and the like. This is particularly true where the desiredproduct is to possess active mercapto groups as it has been found thatthe presence of oxygen and peroxides accelerate the oxidation of themercapto groups into bisulfide linkages.

The reaction may be conducted at atmospheric, superatmospheric orsubatmospheric pressures. It is generally preferred to utilizesuperatmospheric pressures.

At the completion of the reaction, the polymercaptans may be recoveredby a variety of methods obvious to those skilled in the art, such assolvent extraction, filtration, precipitation, distillation, and thelike.

The new products may also be prepared by reacting a polyfunctionalmaterial, such as a polyepoxide, polyhalide, polythiirane andpolythiocyanate wherein the functional elements or groups involveadjacent carbon atoms, with an xanthate so as to form a cyclictrithiocarbonate, and then reducing the trithiocarbonate with a strongreducing agent, such as lithium aluminum hydride, to form thepolymercaptan. This reaction may be illustrated by the following showingthe preparation of bis(2,3-dimercapt0propyl) ether from diglycidylether:

TiAlE4 .The polyepoxides that may be used in this type of reaction maybe exemplified by the polyepoxides described herein for cure with thenew polymercaptans. The polyhalides that may be used include thosecompounds possessing at least two sets of groupings wherein halogenatoms, and preferably chlorine atoms are attached to adjacent carbonatonis, such as, for example,

wherein R is a hydrocarbon radical, such as an alkyl radical as methyl,ethyl and the like, and X is an alkali metal, such as sodium, potassiumand the like. The xanthates are preferably formed in situ byconventional method of reacting carbon disulfide with an alcohol, suchas methanol, and the alkali metal hydroxide, such as sodium or potassiumhydroxide.

The polyfunctional material and the xanthate may be used in a wide rangeof proportions. It is generally preferred to employ the xanthate inexcess and preferably at least 3 to 10 molar excess. In making thexanthate in situ it is preferred to employ an excess of the alcohol sothat it may act as a solvent for the reaction. If the xanthate isprepared ahead of time, it may be desirable to add alcohol to thereaction mixture along with the xanthate so that it may act as thediluent or solvent for the reaction. Other solvents or diluents that maybe employed include inert materials, such as tetrahydrofuran, toluene,benzene, cyclohexane, and the like and mixtures thereof.

The reaction between the polyfunctional material and the xanthate takesplace over a wide range of temperatures. The reaction takes placereadily at the lower temperatures and it is generally preferred toconduct the reaction at temperatures ranging from about 15 C. to 50 C.,and still more preferably between 20 C. and 30 C.

The resulting cyclic trithiocarbonate may be recovered from the reactionmixture or retained therein for reaction with the reducing agent. Thetrithiocarbonate may be recovered if desired .by any suitable means,such as precipitation, filtration, extraction, and the like.

The reducing agent employed in treating the trithiocarbonate may be anystrong reducing agent, such as for example, lithium aluminum hydride,sodium borohydride activated with aluminum chloride and the like. Theseagents are preferably used so as to furnish one mol per trithiocarbonategroup to be reduced, and still more preferably from 1 to 3 moles pertrithioclarbonate group. It is generally preferred to add thetrithiocarbonate to the reducing agent at a slow rate so as to maintainthe mixture at a good reflux rate.

At the completion of the reaction, material, such as alcohol, may beadded to destroy the reducing agent and the reaction mixtureneutralized, washed and otherwise treated to recover the desiredpolymercaptan. This may be accomplished by solvent extraction,filtration, distillation and the like.

The new polymercaptans of the invention will vary from fluid liquids tosolid materials. As indicated above the monomeric products will have thesame structure of the basic polythiirane with the exception that thethiirane group will be replaced with the dirnercaptan group. Thepolymeric products will have repeating units joined through --S groupswith the terminal units possessing the groups.

The new products will be soluble in conventional solvent such asbenzene, xylene, toluene, cyclohexane, cyclohexone, and the like andmixtures thereof. The new polymercaptans will also be compatible withgreat many type of synthetic polymers and tars such as, for example,phenol formaldehyde resins, vinyl resins, coal tar, asphalts, cumeroneresins, protein resins, epoxy resins, polyaldehyde resins, and the like.

The new polymercaptans are also highly reactive components in view of atleast four reactive mercaptan groups and can be combined with a varietyof materials to form new derivatives. For example, as may be reactedwith aldehydes, ketone, anhydrides, acids, epoxy groups and isocyanates,and will add to double bonds under central condition.

The new polymercaptans are particularly useful for use as curing agentsfor polyepoxides. Polyepoxides that may be cured with the newpolymercaptans comprise those materials possessing more than one vicinalepoxy group, i.e., more than one group. These compounds may be saturatedor unsaturated, aliphatic, cycloaliphatic, aromatic or heterocyclic andmay be substituted with substituents, such as chlorine, hydroxyl groups,ether radicals and the like. They may be monomeric or polymeric.

For clarity, many of the polyepoxides and particularly those of thepolymeric type are described in terms of epoxy equivalent values. Themeaning of this expression is described in US. 2,633,458. Thepolyepoxides used in the present process are those having an epoxyequivalency greater than 1.0.

Various examples of polyepoxides that may be used in the process of theinvention are given in U.S. 2,633,- 458 and it is to be understood thatso much of the disclosure of that patent relative to examples ofpolyepoxidesis incorporated by reference into this specification.

Other examples includes the epoxidized esters of the polyethylenicallyunsaturated monocarboxylic acids, such as epoxidized linseed, soybean,perilla, oiticia, tung, walnut and dehydrated castor oil, methyllinoleat, butyl inoleate, ethyl 9,12-octadecadienoate, butyl 9,12,15-octadecatrienoate, butyl eleostearate, monoglycerides of tung oil fattyacids, monoglycerides of soybean oil, sun- 8 flower, rapeseed, hempseed,sardine, cottonseed oil and the like.

Another group of the epoxy-containing materials used in the process ofthe invention include the epoxidized esters of unsaturated monohydricalcohols and polycarboxylic acids, such as, for example,

di(2,3-epoxybutyl) adipate, di(2,3-epoxybutyl) oxalate,di(2,3-epoxyhexyl) succinate, di(3,4-epoxybutyl) maleate,di(2,3-epoxyoctyl) pimelate, di(2,3-epoxybutyl) phthalate,di(2,3-epoxyoctyl) tetrahydrophthalate, di(4,5-epoxydodecyl) maleate,di(2,3-epoxybutyl) terephthalate, di(2,3-epoxypentyl) thiodipropionate,di(5,6-epoxytetradecyl) diphenyldicarboxylate, di(3,4-epoxyheptyl)sulfonyldibutyrate, tri(2,3-epoxybutyl) 1,2,4-butanetricarboxylate,di(5,6-epoxypentadecyl) tartarate, di(4,5-epoxytetradecyl) maleate,di(2,3-epoxybutyl) azelate, di(3,4-epoxybutyl) citrate,di(5,6-epoxyoctyl) cyclohexane-l,Z-dicarboxylate,

hexane-1,2-dicarboxylate, di(4,S-epoxyoctadecyl) malonate.

Another group of the epoxy-containing materials in cludes thoseepoxidized esters of unsaturated alcohols and unsaturated carboxylicacids, such as 2,3-epoxybutyl 3,4-epoxypentanoate, 3,4-epoxyhexyl3,4-epoxyhexyl 3,4-epoxypentanoate, 3,4-ep-oxycyclohexyl 3,4-epoxycyclohexanoate, 3,4-epoxycyc1ohexyl 4,5-epoxyoctanoate,2,3-epoxycyclohexylmethyl epoxycyclohexane carboxylate.

Still another group of the epoxy-containing materials include epoxidizedderivatives of polyethylenically unsaturated polycarboxylic acids suchas, for example,

dimethyl 8,9,12,13 -diepoxyeicosanedioate,

dibutyl 7,8,1 1, l2-diepoxyoctadecanedioate,

dioctyl 10,1 1-diethyl-8,9,12,13-diepoxy-eicosanedioate,

dihexyl 6,7 ,10,1 1-diepoxyhexadecanedioate,

didecyl 9-epoxy-ethyl-10, 1 l-epoxyoctadecanedioate,

dibutyl 3-butyl-3,4,5,6-diepoxycyclohexane-1,2-

dicarboxylate,

dicyclohexyl 3,4,5,6-diepoxycyclohexane-1,2-dicarboxylate,

dibenzyl l,2,4,S-diepoxycyclohexane-1,2-dicarboxylate and diethyl5,6,l0,1l-diepoxyoctadecyl succinate.

Still another group comprises the epoxidized polyesters obtained byreacting an unsaturated polyhydric alcohol and/or unsaturatedpolycarboxylic acid or anhydride groups, such as, for example, thepolyester obtained by reacting 8,9,12,13-eicosanedienedioic acid withethylene glycol, the polyester obtained by reacting diethylene glycolwith 2-cyclohexene-1,4-dicarboxylic acid and the like, and mixturesthereof.

Still another group comprises the epoxidized polyethylenicallyunsaturated hydrocarbons, such as epoxidized 2,2-bis(2-cyclohexenyl)propane, epoxidized vinyl cyclohexene and epoxidized dimer ofcyclopentadiene.

Another group comprises the epoxidized polymers and copolymers ofdiolefins, such as butadiene. Examples of this include, among others,butadiene-acrylonitrile copolymers (Hycar rubbers), butadiene-styrenecopolymers and the like.

Another group comprises the glycidyl containing nitrogen compounds, suchas diglycidyl aniline and diand triglycidylamine.

The polyepoxides that are particularly preferred for use in thecompositions of the invention are the glycidyl ethers and particularlythe glycidyl ethers of polyhydric phenols and polyhydric alcohols. Theglycidyl ethers of 9 polyhydric phenols are obtained by reactingepichlorohydrin with the desired polyhydric phenols in the presence ofalkali. Polyether A and Polyether B described in the above-noted US2,633,458 are good examples of polyepoxides of this type. Other examplesinclude the polyglycidyl ether of1,1,2,2-tetrakis(4-hydroxyphenyl)ethane (epoxy value of 0.45 eq./100 g.and melting point 85 C.), polyglycidyl ether of 1,1,5,5-tetrakis(hydroxyphenol) pentane (epoxy value of 0.514 eq./ 100 g.) and the likeand mixtures thereof.

The amount of new polymercaptans to be employed in the cure of thepolyepoxide may vary within certain limits. In general, the polyepoxidesare combined with at least .8 equivalents of the polymercaptan. As usedherein equivalen amount refers to that amount needed to furthe cure.Examples of these include, among others, phenols, sulfides, mercaptans,organic phosphines, organic arsines, organic antimony compounds, amines,amine salts of quaternary ammonium salts, etc. Preferred activatorsarethe phenols, phosphines, arsines, amines, and sulfides,-

such as, for example benzyldimethylamine dicyandiamidep,p'-bis(dimethylaminophenyl) methane, pyridine, dimethyl aniline,dimethylethanolamine, methyldiethanoL amine, morpholine,dimethylaminopropylamine, dibutylaminopropylamine, stearyldimethylamine,tri n butyl amine, N,N-dibutyl butylamine, tri-n-hexylamine, ethyldi-n-propylamine, phenylene diamine, diethylene triamine, dibutylsulfide, dioctyl sulfide, dicyclohexyl sulfide and the like, andmixtures thereof. The salts may be exemplified by the inorganic andorganic acid salts of the amines, such as, for example, thehydrochloride, sulfate and acetate of each of the above-describedtertiary amines. The quaternary ammonium salts may be exemplified by thefollowing: benzyltrirnethylammonium chloride, phenyltributylammoniumchloride, cyclohexyltributylammonium sulfate, benzyltrimethylammoniumsulfate, benzyltrimethylammonium borate, diphenyldioctylammoniumchloride, and the like, and mixtures thereof.

Preferred activators to be used are the sulfides, phosphines andtertiary amines, and more preferably the monoand diamines wherein theamine hydrogens have been replaced by aliphatic, cycloaliphatic oraromatic hydrocarbon radicals containing not more than 15 carbon atoms,such as, for example, the trialkyl amines, triaryl amines,triarylalkylamines, alkyl arylalkylamines, tricycloalkylamines, alkyldicycloalkylamines, diaminoalkanes, dialkylene triamines, phenylenediamines and di (aminoaryl) alkanes. Preferred amine salts are thehydrochloride, sulfate and acetate of the above-described preferredamines. The preferred quaternary salts are thoseof the formula R I 50 \Rx wherein Y is nitrogen, R is an alkyl, aryl or arylalkyl radical,preferably containing no more than 12 carbon atoms and X is chlorine.

The activators noted above are generally employed in amounts varyingfrom 0.1 part to 4 parts per 100 parts of polyepoxide, and preferablyfrom 1 part to 3 parts per 100 parts of polyepoxide.

In curing the polyepoxides, it is usually desirable to have thepolyepoxide in a mobile condition when the polymercaptan is added inorder to facilitate mixing. The polyepoxides, such as the glycidylpolyether of polyhydric phenols, are generally very viscous to solidmaterials at ordinary temperature. With those that are liquid, but tooviscous for ready mixing, they are either heated to reduce theviscosity, or have a liquid solvent added thereto in order to providefluidity. Normally solid members are likewise either melted or mixedwith a liquid solvent. Various solvents are suitable for achievingfluidity of the polyepoxide. These may be volatile solvents which escapefrom the polyepoxide compositions containing the adduct by, evaporationbefore or during the curing such as esters such as ethyl acetate, butylacetate, Cellosolve acetate (ethylene glycol monoacetate), methylCellosolve acetate (acetate ethylene glycol monomethyl ether), etc.,ether alcohols, such as methyl, ethyl or butyl ether of ethylene glycolor diethylene glycol; chlorinated hydrocarbons such as trichloropropane,chloroform, etc. To save expense, these active solvents may be used inadmixture with aromatic hydrocarbons such as benzene, toluene, xylene,etc., and/or alcohols such as ethyl, isopropyl or n-butyl alcohol.Solvents which remain in the cured compositions may also be used, suchas diethyl phthalate, dibutyl phthalate and the like, as well ascyano-substituted hydrocarbons, such as acetonitrile, propionitrile,adiponitrile, benzonitrile, and the like. It is also convenient toemploy a polyepoxide, such as one of the glycidyl polyethers of thedihydric phenol, in admixture with a normal- 1y liquid glycidylpolyether of a polyhydric alcohol. In fact, two or more of any of thepolyepoxides may be used together as mixtures. In such a case, theamount of the adduct added and commingled is based on the averageepoxide equivalent Weight of the polyepoxide mixture.

Various other ingredients may be mixed with the polyepoxide subjected tocure with the novel adducts including pigments, filler, dyes,plasticizers, resins, and the like.

The polyepoxides may be cured with the new polymercaptans by merelymixing the two components together, preferably in the presence of theabove-noted activators. The cure time may vary for a few hours to a fewdays depending on the type and quantity of reactants and presence ofcatalyst. In generally, in the presence ,of activators, the cure takesplace readily at room temperature. Fast reaction may be obtained, ofcourse, by applying heat. Preferred temperatures range from about 20 C.to 200 C. With small castings, it is preferred to cure at roomtemperature and then post cure for a few hours at elevated temperatures,say 40 C. to C.

One important application of the use of the new polymercaptans as curingagents for polyepoxides is in the preparation of laminates or resinousparticles reinforced with fibrous textiles. Although it is generallypreferred to utilize glass cloth for this purpose, any of the othersuitable fibrous materials in sheet form may be employed such as glassmatting, paper, abestox paper, mica flakes, cotton batts, duck muslin,canvas and the like. It is useful to prepare the laminates from wovenglass cloth that has been given prior treatment with well knownfinishing or sizing agents therefor, such :as chrome methacrylate .orvinyl trichlorosilane.

In preparing the laminate, the sheets of fibrous materials -arepreferably first impregnated with the mixture of the polyepoxide,polymercaptan and activator. This is conveniently accomplished bydissolving the polymercaptan in a solvent and mixing the solution withthe polyepoxide so as to obtain a fluid mixture. The sheets of fibrousmaterial are impregnated with the mixture by spreading it thereon or bydipping or otherwise immersing them in the'impregnant. The solvent isconveniently removed by evaporation and the mixture is cured by theapplication of heat. A plurality of the impregnated sheets can besuperimposed and the assembly cured in a heated press under a pressureof about 25 to 500 or more pounds per square inch. The resultinglaminate is extremely strong and resistant against the action of organicand corrosive solvents.

The new compositions of the invention are particularly outstanding asadhesives. In this application they can be used as a paste or solutiondepending on the method of preparation as described. Other materials mayalso be included in the composition, such as pigments, plasticizers,

stabilizers and reinforcing fillers, such as aluminum powder, asbestos,powdered mica, zinc dust, bentonite, ground glass fibers, Monetta clayand the like. These fillers are preferably used in amounts varying fromabout parts to 200 parts per 100 parts of the polyepoxide andpolymercaptan compound. Other materials that may be included includeother types of resins, such as phenolaldehyde resins, urea-aldehyderesins, furfural resins, polyacetal resins, carbonate resins, polyamideresins, and the like.

The compositions may be used in the bonding of a great variety ofdifferent materials, such as metal-to-metal to other materials, such asplastic, wood-to-wood, glass-toglass, glass-to-metal, and the like. Theyare of particular value, however, in the bonding of metals such asaluminum-to-aluminum and steel-to-steel. When applied as an adhesive,the compositions may simply be spread on the desired surface to formfilms of various thicknesses, e.g., 0.5 mil to 30 mils, and then theother surface superimposed and heat applied. Curing pressures can belight con tact pressures up to about 500 p.s.i.

When the compositions are used as adhesives for metalto-metal bonding,it has sometimes been found advantageous to impregnate cotton, rayon,synthetic fiber or glass cloth textiles with the compositions, and thenuse the impregnated textiles as a bonding tape for joining the metals.Such tapes provide convenient means for handling and using thecompositions in adhesive applications. The tape is inserted between twometals desired to be joined, and the assembly is heated and baked tocure the resin whereby articles are obtained wherein the joined surfaceshave not only excellent strength at ordinary temperatures, but alsoretain good strength even though heated at quite elevated temperaturesfor long periods of time. A preferred tape for such use comprises aglass fiber textile impregnated or coated with a mixture of thepolyepoxide, phthalocyanine compound and atomized aluminum powder ordust.

To illustrate the manner in which the invention may be carried out thefollowing examples are given. It is to be understood, however, that theexamples are for the purpose of illustration and that the invention isnot to be regarded as limited to any of the specific conditions orreactants recited therein. Unless otherwise specified parts described inthe examples are parts by weight.

Example I This example illustrates the preparation and some of theproperties of 1-(l,2-dimercaptoethyl) 3,4-dimercaptocyclohexane.

1500 parts of potassium hydroxide was placed in a reaction vessel and5500 parts of methanol added thereto. The temperature arose to about 70C. and the vessel was cooled to room temperature. 2440 parts of carbondisultide was then added at 30 C. Vinylcyclohexene dioxide was pumpedinto the reaction vessel at the rate of about .5 part per minute. Afterthe addition of about 750 parts of the vinylcyclohexene dioxide, themixture was stirred for about 60 hours. 3000 parts of water were thenadded and most of the excess carbon disulfide and methanol removed undervacuum keeping the temperature below 30 C. The precipitate was washedwith water and then acetone and dried. The yellow solid precipitate hada melting range of 145-l53 C. and contained 55.8% sulfur. The productwas identified as having the structure:

S ll S S CH Ha The -above-noted thiocarbonate was reduced to the desiredpolymercaptan in the following manner. 2000 parts of tetrahydrofuran,500 parts of diethyl ether and 280 parts of lithium aluminum hydridewere charged to a reaction vessel and the mixture stirred. Theabove-noted thiocarbonate was added to 3000 parts of tetrahydrofuran andthe resulting slurry was added slowly to the reaction vessel containingthe lithium aluminum hydride so as to maintain a good reflux rate over aperiod of about 2 hours. The mixture was then cooled to 0 C. and 1300parts of water added. 3000 parts of concentrated HCl was added. Themixture was stirred for 60 hours. The mixture separated into two layers,a clear yellow layer over a grey water layer. The excess acid wasneutralized and the organic layer removed. The organic ether layer waswashed, dried and the solvent stripped at 50 C. under vacuum to give thecrude tetramercaptan. This product was purified by moleculardistillation yielding a light yellow liquid identified as1-(1,2-dimercaptoethyl) 3,4 dimercaptocyclohexane SH equivalency 1.59eq./ g.

About 100 parts of diglycidyl ether of 2,2-bis(4-hydroxyphenyl)propanewas combined with an equivalent amount of the above-describedpolymercaptan and 1% by Weight of benzyldimethylamine and the mixtureheated at 100 C. The mixture set up to form a hard insoluble casting.

Example II This example illustrates the preparation and some of theproperties of a polymercaptan prepared from di(2,3- epithiopropyl ether)of 2,2-bis(4-hydroxyphenyl) propane.

Into a reaction vessel equipped with a stirrer, addition funnel and an H8 addition tube were placed 400 parts of acetonitrile. Hydrogen sulfidewas bubbled into the acetonitrile until it was saturated. A solution of50 parts of di(2,3-epithiopropyl ether) of2,2-bis(4-hydroxyphenyl)propane in 300 parts of acetonitrile was addeddropwise to the hydrogen sulfide-acetonitrile solution with continuousstirring and addition of hydrogen sulfide gas over a period of about 5hours. After the addition was complete, the reaction mixture was stirredfor another 30 minutes with continuous hydrogen sulfide addition. At theend of this time, the reaction mixture was filtered to remove a smallamount of insoluble matter and the filtrate was concentrated in vacuo,avoiding as much as possible any contact with air. The residue, aslightly yellow solid was dried at high vacuum and room temperature.Yield of crude product was 44 parts. The product identified asdi(2,3-dimercaptopropyl ether) of 2,2-bis(4-hydroxyphenyl)propanecontained 25.3% sulfur and mercapt-an equivalency of 0.77 eq./100 'g.

About 100 parts of diglycidyl ether of 2,2-bis(4-hydroxyphenyl)propanewas combined with an equivalent amount of the above-describedpolymercaptan and 1% by weight of benzyldimethylamine and the mixtureheated at 100 C. The mixture set up to form a hard insoluble casting.

Example III This example illustrates the preparation and some of theproperties of bis(2,3-dimercaptopropyl)ether.

216 parts of KOH was placed in a reaction vessel and 740 parts ofmethanol added thereto. The temperature arose to about 70 C. and thevessel was cooled to room temperature. 350 parts of carbon disulfide wasthen added to the vessel slowly with stirring. 100 parts of diglycidylether was added dropwise with stirring. The reaction mixture was thenstirred at room temperature for about 24 hours. 1000 parts of water wasthen added and the carbon disulfide and methanol were distilled offunder vacuum. The precipitate was extracted with chloroform and washedwith water to a neutral pH. The product was then stripped of solvent anddried. The resulting '13 product was a yellow crystalling solididentified as the thioca rbonate 57.9% sulfur.

The above-described thiocarbonate was reduced to the desiredpolymercaptan in the following manner. 295 parts of lithium aluminumhydride was charged to a reaction vessel equipped with stirrer,condenser and dropping funnel. 2500 parts of anhydrous ether was addedto the flask. 753 parts of the carbonate prepared above was dissolved in2500 tetrahydrofuran and this mixture added dropwise with stirring tothe reaction vessel containing the lithium aluminum hydride. Theaddition was accomplished over a one hour period and the stirring wascontinued for another 45 minutes. The reactants were then heated toreflux and about 2000 parts of the ether removed. The contents were thencooled and kept at -5" C. and water added (about 1500 parts). 800 partsof concentrated HCl was added followed by 1000 parts of water and then1700 more parts of concentrated HCl. The mixture separated into twolayers. The top organic layer was removed, Washed, dried and solventstripped under vacuum. The product was distilled in a molecular still togive a clear, light yellow liquid identified asbis(2,3-dimercaptopropyl) ether.

About 100 parts of diglycidyl ether of 2,2-bis(4-hydroxyphenyl)propanewas combined with an equivalent amount of the above-describedpolymercaptan and 1% by weight of benzyldimethylamine and the mixtureheated at 100 C; The resulting product was a hard insoluble casting.

Example IV Example V The preceding example was repeated with theexception that the mixture was allowed to cure at room temperature. Theresulting cured product was hard and tough and had good flexibility.

I claim as my invention:

1. A polymercaptan of the group consisting of (1) polymercaptanpolyethers of the formula sH SH wherein n is 2 to 6 and R is anunsubstituted hydrocarbon radical,

(2) polymercaptan polyesters of the formula ((6 SIH sH \-C-0'CH2CHCH2)wherein n is an integer of 2 to 6 and R is an unsubstituted hydrocarbonradical, and (3) polymercaptan-substituted hydrocarbons of the for- 14wherein X is an integer of 0 to 6, n is an integer of 2 to 6 and R is anunsubstituted hydrocarbon radical. 2. A polymercaptan of the formula 5 sn SIH R-OOHaCH-CH) H wherein n is 2 to 6 and the R is an unsubstitutedhydrocarbon radical.

3. A polymercaptan of the formula SH SH wherein n is an integer of 2 to6 and R is an unsubstituted hydrocarbon radical.

4. A polymercaptan of the formula SE s n FOE: l3HCH2 u wherein X is aninteger of 0 to 6, n is an integer of from 2 to 6 and R is anunsubstituted hydrocarbon radical.

5. A cyclic polymercaptan of the formula wherein R is a --(CH radicalwherein n is 0 to 10.

7. Di(2,3-dimercaptopropyl)ether.

8. 1-( 1,2-dimercaptoethyl) -3,4dimercaptocyclohexane.

9. 23-dimercaptopropyl ether of 2,2-bis(4 hydroxyphenyl propane.

10. A process for preparing polymercaptans as described in claim 1 whichcomprises reacting a polythiirane compound of the group consisting of(1) polythiiranes of the formula wherein n is 2 to 6 and R is anunsubstituted hydrocarbon radical, (2) polythiiranes of the formulawherein n is an integer of 2 to 6 and R stituted hydrocarbon radical,(3) polythiiranes of the formula wherein X is an integer of 0 to 6, n isan integer of 2 to 6 and R is an unsubstituted hydrocarbon radical,

with hydrogen sulfide in an equivalent ratio of H 8 to epoxide of 5:1 to:1 in the substantial absence of molecular oxygen.

11. A process for preparing polymercaptans which comprises reacting apolythiirane of the formula is a bn unsu CTr CHCHg-OROCHnOfi OHz whereinR is an unsubstituted hydrocarbon with hydrogen sulfide in an equivalentratio of hydrogen sulfide to polythiirane of 5 :1 to 50:1 in thesubstantial absence of molecular oxygen.

(References on following page) References Cited 3,072,606 1/1963Zuppinger 260- 17 3,076,848 2/ 1963 Laufer 260-609 UNITED STATES PATENTS3,076,851 2/1963 Neuworth 260609 2,995,569 8/1961 Hamilton 260327 3Slszak 5 A. Primal} Examiner.

3 057 171 12 1952 Hoppe 2 47 T. L. GALLOWAY, Assistant Examiner.

1. A POLYMERCAPTAN OF THE GROUP CONSISTING OF (1) POLYMERCAPTANPOLYETHERS OF THE FORMULA
 10. A PROCESS FOR PREPARING POLYMERCAPTANS ASDESCRIBED IN CLAIM 1 WHICH COMPRISES REACTING A POLYTHIIRANE COMPOUND OFTHE GROUP CONSISTING OF (1) POLYTHIIRANES OF THE FORMULA